The present invention relates generally to locomotives, and more particularly to a locomotive diagnostic system.
Locomotives include diesel-electric locomotives used by railroads to haul passengers and freight. Current locomotive diagnostic systems include traction speed sensors and water and oil temperature and pressure sensors which give an overall indication that there is a present problem with the locomotive but do not indicate the specific component or cause of the problem. Federal regulations require that locomotives be serviced every 92 days. While in the shop, each locomotive undergoes a conventional service and maintenance check up. Such check ups include partial locomotive disassembly to expose replaceable units and visual inspection and possibly electrical testing of the replaceable units for problems (such as visual inspection for scorch marks or a xe2x80x9cfrozenxe2x80x9d fan rotor or electrical testing of a fan for proper operation). Defective replaceable units are replaced. A replaceable unit (RU) is the smallest replaceable assembly of parts. For example, locomotives have several fans needed to cool various components including the motor or motors. Badly worn fan bearings eventually will lead to cooling fan stoppage, and a locomotive motor can overheat and fail without adequate cooling from a cooling fan. The cooling fan, and not the fan bearing, is the replaceable unit. A locomotive that becomes disabled while in operation between shop visits is a cost liability to the railroad.
What is needed is a system and method for identification of problem (i.e., soon-to-fail) replaceable units (RU""s) of a locomotive before these problem units actually fail.
In a first embodiment, the locomotive diagnostic system is for a locomotive having a first component (such as a bearing set of a blower fan) and a second component (such as a shaft of the blower fan). The system includes a first sensor which is located in sensing proximity to the first component and which outputs a measurement of a first state variable (such as vibration) of the first component. The first state variable is indicative of the operation of the first component, and the first state variable is dependent on a second state variable (such as rotational speed) of the second component. The system also includes a second sensor which is located in sensing proximity to the second component and which outputs a measurement of the second state variable. The system additionally includes data representing, for each of a number of different values of the second state variable, a first range of values of the first state variable which indicates a normal operation of the first component, a second range of values of the first state variable which indicates a worn operation of the first component, and a third range of values of the first state variable which indicates a failed operation of the first component. The system moreover includes a mechanism for determining if the measurement of the first state variable is within the first, second, or third range of values of the first state variable for the measurement of the second state variable.
In one example, the mechanism is a computer which directs the first and second sensors to take additional measurement, which calculates a deterioration rate of the first state variable from the additional measurements, and which predicts a time-to-failure for the first component based on a latest measurement of the first state variable, the deterioration rate, and the data.
In another example, the system also includes an additional sensor which is located in sensing proximity to the first component, which outputs a measurement of an additional state variable (such as acoustic noise) of the first component. The additional state variable is indicative of the operation of the first component, and the additional state variable is dependent on the second state variable of the second component.
Several benefits and advantages are derived from the invention. The locomotive diagnostic system of the invention indicates to the railroad that a locomotive component is worn and needs replacement. The locomotive diagnostic system of the invention also gives the railroad a prediction of the time-to-failure of the locomotive component. Knowing a predicted time-to-failure allows the railroad to minimize locomotive downtime by replacing the worn locomotive component (or the larger replaceable unit containing the component if the component itself is not replaced) before the component fails while the locomotive is hauling passengers or freight.